PROJECT SUMMARY/ABSTRACT Perinatal asphyxia (PA), where newborn infants suffer from a lack of oxygen and blood flow to the brain, is a leading cause of morbidity and mortality around the time of birth. PA in term infants, and the resulting neurodevelopmental sequelae such as intellectual disability, cerebral palsy, epilepsy, and hearing or vision impairment, result in a huge burden to society. Current therapies such as therapeutic hypothermia have a limited effect (15% reduction ins death or disability), and are not curative. We propose to develop an effective neuroprotective treatment using enzyme- loaded nanoparticles in a neonatal model of hypoxia-ischemic (HI) brain injury. Cellular oxidative stress often begins with the production of superoxide, for example, within the electron transport chain of dysfunctional mitochondria after HI brain injury. Superoxide is primarily scavenged by superoxide dismutase (SOD), catalyzing its dismutation anion to hydrogen peroxide,43 which is then converted to water and oxygen by catalase. The cooperative action of these multiple enzymes is crucial to the successful clearance of reactive oxygen species. For instance, while SOD overexpression is neuroprotective in a rodent model of adult stroke, it may exacerbate injury in the neonatal brain due to a relative under-expression of catalase, resulting in accumulation of hydrogen peroxide. Therefore, precisely-targeted and controlled co-delivery of cooperative antioxidant enzymes has significant potential for ameliorating oxidative stress in the setting of neonatal HI brain injury. Therefore, we will investigate the neuroprotective capability of combined catalase-loaded and SOD-loaded nanoparticles in a neonatal rodent model of term HI brain injury. The first aim focuses on determining the biodistribution and effective dose of SOD-loaded and catalase-loaded poly(lactic-co-glycolic)-poly(ethylene glycol) (PLGA-PEG) nanoparticles. The second aim will evaluate the efficacy of a combined delivery of SOD-loaded and catalase-loaded PLGA-PEG nanoparticles to determine the neuroprotective effects in newborn rats with HI in comparison to free drug and saline treated controls. This study is significant because it explores the potential of nanomedicine-based therapy for neuroprotection in a clinically-relevant model of neonatal HI, with implications for other perinatal brain injuries that share pathological hallmarks.